One out of 10 American high school students used e-cigarettes in 2012, along with nearly three in 100 middle-school students, according to a new federal report. That’s about double the rate of e-cigarette use in 2011.

The sharp increase has public health experts worried. Electronic cigarettes contain nicotine, an enticing flavor like mint or chocolate -- and often cancer-causing compounds called nitrosamines, according to a 2009 analysis by the Food and Drug Administration.

“The increased use of e-cigarettes by teens is deeply troubling,” Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, said in a statement. “Many teens who start with e-cigarettes may be condemned to struggling with a lifelong addiction to nicotine and conventional cigarettes.”

The study, published in Friday’s edition of the CDC’s Morbidity and Mortality Weekly Report, is based on data from the National Youth Tobacco Survey. It found that 1.1% of students in grades six through eight were using e-cigarettes at least once a month, as were 2.8% of students in grades nine to 12.

Among these regular e-cigarette users, 76.3% also smoked traditional cigarettes. But the report’s authors -- from the FDA’s Center for Tobacco Products and the CDC’s Office on Smoking and Health -- seemed most concerned about the 20.3% of middle-school students and 7.2% of high schoolers who had used e-cigarettes but not yet tried conventional cigarettes. The researchers estimated that 160,000 students across the country fell into that category.

“The risk for nicotine addiction and initiation of the use of conventional cigarettes or other tobacco products” among these students is a “serious concern,” they wrote.

Electronic cigarettes are not regulated by the FDA, though the agency has said it plans to bring the battery-powered devices under its jurisdiction. In the meantime, some cities are setting limits on their use.

If the idea is to nip e-cigs in the bud before they take off with consumers, it’s probably too late. One tobacco industry analyst from Wells Fargo Securities predicts Americans will spend $1.7 billion on e-cigarettes this year. That means experts at the FDA and CDC should get busy, the study authors wrote:

“Given the rapid increase in use and youths’ susceptibility to social and environmental influences to use tobacco, developing strategies to prevent marketing, sales, and use of e-cigarettes among youths is critical.”

[For the record, 1:45 p.m. PDT Sept. 5: An earlier version of this post said that three in 10 middle-school students had tried e-cigarettes. The ratio is three in 100 students.]